NFC technology allows for communications between a mobile device (e.g., an NFC-enabled mobile phone or a smart card with an NFC/RFID tag) and an NFC reader (e.g., in a point-of-sale terminal or another mobile device) over a distance of several centimeters or less. To initiate communications, an NFC device first recognizes that another NFC device is within range. Traditional techniques that involve periodic polling consume excessive amounts of power and may be too elaborate to be performed frequently. Accordingly, there is a need for efficient techniques for an NFC device to detect the presence of another NFC device.
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